docs: def get_serial_port():
      """ Return serial.Serial instance, ready to use for RS485."""
      port = Serial(port='/dev/ttyS1', baudrate=9600, parity=PARITY_NONE,
                    stopbits=1, bytesize=8, timeout=1)
  
      fh = port.fileno()
  
      # A struct with configuration for serial port.
      serial_rs485 = struct.pack('hhhhhhhh', 1, 0, 0, 0, 0, 0, 0, 0)
      fcntl.ioctl(fh, 0x542F, serial_rs485)
  
      return port